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Abstract

In the title triangulo-triruthenium compound, [Ru3(C18H12Cl3P)(CO)11], one equatorial carbonyl group has been substituted by the monodentate phosphine ligand, leaving one equatorial and two axial carbonyl substituents on the Ru atom. The remaining two Ru atoms each carry two equatorial and two axial terminal carbonyl ligands. The three benzene rings make dihedral angles of 87.83 (17), 69.91 (17) and 68.26 (17)° with each other. In the crystal structure, mol­ecules are linked into dimers by inter­molecular C—HO hydrogen bonds. The mol­ecular structure is stabilized by an intra­molecular C—HO hydrogen bond.

Acknowledgments

We gratefully acknowledge funding from the Malaysian Government and Universiti Sains Malaysia (USM) under the University Research Grant 1001/PJJAUH/811115. MAAP thanks USM for a post-doctoral fellowship, HKF thanks USM for the Research University Golden Goose Grant 1001/PFIZIK/811012 and CSY thanks USM for the award of a USM Fellowship.

supplementary crystallographic
information

Comment

Syntheses and structures of substituted triangulo-triruthenium clusters
have been of interest to researchers due to observed structural variations and
their potential catalytic activity. As part of our ongoing
studies on phosphine substituted triangulo-triruthenium clusters,
herein we report the structure of title compound (I).

In the title compound (I), the monodentate phosphine ligand has replaced a
single carbonyl group in the equatorial plane of the Ru3 triangle.
The triangulo-triruthenium is bonded equatorially to a monodentate
phosphine ligand. The Ru1–Ru2 bond is noticeably
longer [2.9002 (4) Å] compared to the other two Ru–Ru bonds [2.8600 (3) and
2.8611 (4) Å]. The unusual increase in the length of Ru–Ru bond in
comparison to those in Ru3(CO)12 (Churchill et al.,
1977), can be attributed to the steric effect induced by the bulky
substituent.

As observed in Ru3(CO)12, the bond from metal atoms to the axial CO ligands
in complex (I) are longer (Ru–C(ave) = 1.934 Å) compared to the equatorial
CO groups (Ru–C(ave) = 1.918 Å). The equatorial Ru–C–O substituents are
linear (average value: 177.94°) while the axial Ru–C–O ligands are slightly
bent (average value: 173.55°). Similar observations were made by Bruce and
co-workers for the range of monosubstituted complexes they synthesized (Bruce
et al., 1988).

The three phosphine-substituted benzene rings make dihedral angles
(C1–C6/C7–C12, C1–C6/C13–C18 and C7–C12/C13–C18) of 87.83 (17), 69.91
(17) and 68.26 (17)° with each other respectively. In the crystal structure,
the molecules are linked into dimers by intermolecular C17—H17A···O5
hydrogen bonds (Fig. 2, Table 1). The molecular structure is stabilized by an
intramolecular C18—H18A···O3 hydrogen bond.

Experimental

All the manipulations were performed under a dry oxygen-free nitrogen
atmosphere using standard Schlenk techniques. THF was dried over sodium wire
and freshly distilled from sodium benzophenone ketyl solution. The title
compound (I) was prepared by mixing Ru3(CO)12 (Aldrich) and
P(3-Cl-C6H4)3 (Maybridge) in a 1:1 molar ratio in THF at 40 °C. About
0.2 ml of diphenylketyl radical anion initiator (synthesized as per the method
of Bruce et al., 1987) was introduced into the reaction mixture
under a
current of nitrogen. After 15 min. of stirring, the solvent was removed under
vacuum. Separation of the product in the pure form was done by column
chromatography (Florisil, 100-200 mesh, eluant, dichloromethane: hexane).
IR (cyclohexane): ν (CO) 2100, 2049, 2033 and 2019 cm-1. 1H-NMR (CDCl3,
δ); 7.23-7.25 (m, aromatic protons). Crystals suitable for X-ray diffraction
were grown from n-pentane solution at 10°C.

Refinement

All hydrogen atoms were positioned geometrically and refined using a riding
model with C—H = 0.93 Å and Uiso(H) = 1.2 Ueq(C).

Special details

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are
estimated using the full covariance matrix. The cell esds are taken into
account individually in the estimation of esds in distances, angles and
torsion angles; correlations between esds in cell parameters are only used
when they are defined by crystal symmetry. An approximate (isotropic)
treatment of cell esds is used for estimating esds involving l.s. planes.

Refinement. Refinement of F2 against ALL reflections. The weighted R-factor
wR and goodness of fit S are based on F2, conventional
R-factors R are based on F, with F set to zero for
negative F2. The threshold expression of F2 >
σ(F2) is used only for calculating R-factors(gt) etc. and is
not relevant to the choice of reflections for refinement. R-factors
based on F2 are statistically about twice as large as those based on
F, and R- factors based on ALL data will be even larger.